1. Field of the Disclosure
The present disclosure relates generally to waveguides and, more particularly, to optical waveguides.
2. Description of Related Art
Optical devices for high power applications often invoke some manner of dimensional scale-down of the optical waveguide boundaries, for the purpose of concentrating or combining power into a smaller fiber guide. For example, a tapered fiber bundle forms a composite waveguide of fused fibers, which is then tapered to reduce its diameter. Unfortunately, this tapering results in an increase of the numerical aperture (NA) of the beam. Thus, in order to prevent loss of light in these types of tapered waveguides, the NA at an input must be sufficiently small that any eventual increase in NA does not exceed a critical angle and the waveguide maintains total internal reflection.